Optimization of fiber orientation for reducing notch sensitivity in vacuum-assisted resin infused composite materials

Document Type : Research Paper

Authors

¹ College of Materials Engineering, University of Technology – Iraq, Baghdad, Iraq.

² Department of Mechanical and Automobile Engineering, Technological University of the Shannon, Limerick V94EC5T, Ireland.

³ Hydrogen Energy Innovation (HEI) Research Group, Technological University of the Shannon, Limerick V94EC5T, Ireland.

10.30772/qjes.2026.164571.1724

Abstract

This work examines notch sensitivity in fiber-reinforced polymer composites, with attention to the role of fiber orientation and notch width. CFRP and GFRP specimens were fabricated by vacuum-assisted resin transfer molding (VARTM) using thermoset resin systems. The tested variables were fiber orientation (0^o and 90^o), notch width (0, 2, 4, and 6 mm), and tensile tests were carried out according to ASTM D638. The results showed that the 0° specimens had noticeably higher strength than the 90^o specimens because the fibers were aligned with the loading direction. The 90^o specimens showed lower strength and a more gradual failure response, mainly due to matrix-dominated behavior. Increasing the notch width reduced the ultimate tensile strength, especially for 4 and 6 mm notches, where fracture started near the notch tip because of stress concentration. Unnotched and 2 mm notched specimens provided the best balance between strength retention and practical manufacturability. These results confirm that careful fiber alignment and notch control are important for composite parts used in aerospace, automotive, and civil engineering structures

Keywords

Subjects

• Mechanical Engineering